Presently, most radios require some form of manual tuning of the antenna of the radio and/or the radio itself, in the factory, prior to shipment. Such tuning procedures, external test equipment, special test fixtures, and trained personnel are required. In addition, the tuning procedures can be quite costly and increase the manufacturing time of a radio. This is partly due to the fact that newer radios often utilize ultra or sub-miniature components which may require specialized tools and test equipment for proper tuning.
Once these tuning procedures or tuning adjustments are completed in the factory, it is quite possible that the radio will have to be re-adjusted in the future due to degradation of the electronic components within the radio circuitry or a change of frequency or operating environment of the radio. This can require for instance, the radio being taken out of service by the subscriber, and then sent back to the factory or service depot for readjustment.
If the radio includes a transmitter or is a transceiver, antenna tuning is typically accomplished by using the radio's transmitter and the required internal circuitry or external test equipment to measure the voltage standing wave ratio (VSWR), the forward or reflected radio frequency (RF) power, or the return loss and adjusting the transmitter accordingly for the most optimum performance. If the radio is a transceiver (a radio including both a transmitter and a receiver in the same package using the same antenna) the tuning accomplished between the transmitter and the antenna, may have to suffice for the receiver as well. This design is typically acceptable, however, the tuning or coupling between the antenna and receiver, may be less then optimum, thus degrading the sensitivity or other characteristics of the radio receiver.
Still, other radio systems include stand alone receivers which, require tuning between the antenna and the receiver RF circuitry, but provide for few acceptable methods for accomplishing this in the field without external test equipment.
Another aspect may be the re-tuning of an antenna with a radio for a change in frequency, location, system, or for ever changing environmental conditions in the radio coverage area to enhance a radios performance at all times of operation.
Clearly, a need exists for an approach to accurately, cost effectively and rapidly, self-tune a radios antenna to a radio receiver or transceiver without special tools, test equipment, or trained personnel in the field.
A method and apparatus that can automatically accomplish antenna tuning with a radio receiver is highly desirable.